Work stop mechanism



July 31, 1956 A. F. PRANGE WORK STOP MECHANISU Filed June 15, 1953 3 Sheets-Sheet 1 z wd irrapme-ys July 31, 1956 F. PRANGE 2,756,820

woax STOP MECHANISM Filed June 15, 1953 3 Sheets-Sheet 2 ivroz/vsys July 31, 1956 PRANGE 2,756,820

WORK STQP MECHANISM Filed June 15, 1953 3 Sheets-Sheet 3 I W 5 1 I 1 F IGJO.

m 4 4mm? F PPM 4 United States Patent Ofiice 2,756,820 Patented July 31, 1956 WORK sror MECHANISM Alfons F. Prange, St. Louis, Mo.; Mary Prange, executrix of said Alfons F. Prange, deceased Application June 15, 1953, Serial No. 361,803

11 Claims. (Cl. 164-69) This invention relates to a work stop mechanism such as may be mounted on one side of a plate along the other side of which stock may be positioned for recessing at predetermined intervals. It has particular application to work stops, both automatic and manually operated, for punch-press dies. However, it has numerous other important applications.

The term plate is used herein broadly to include any suitable work surface through which a stop pin can extend to engage a piece of stock, such, for example, as the fiat stripper plate of the usual punch-press die set, or a curved plate such as might be used in drilling or punching radially a cylindrical surface.

The term stock is used herein to indicate any kind of material in any shape or form which admits of being recessed at predetermined space intervals.

The verb recessed is used herein to indicate an operation wherein stock is punched, drilled, reamed, milled, or otherwise cut out or indented.

By way of background for the embodiment of the stop mechanism of this invention used as an automatic diestop, various automatic die-stops have been known heretofore. The devices of patents to Danly, No. 1,495,989, Besocke, No. 1,927,885, and Kowalski, No. 2,254,659, are representative of automatic die-stops of the prior art. These die-stops have had various disadvantages. Those devices typified by Danly and Besocke have required that the stripper plate on which they are mounted be milled out to receive the rocker arm. In addition, the arrangement of the stop pin of those devices has been such that it is normally biased to a vertical position, but is moved to an oblique position by the stock. This tends, particularly when the stock is of light gauge, to lift the pin and allow the stock to pass under it. In fl-ie die-stop of Kowalski, the stop pin is grooved axially and a thin wire spring extends along the groove and is pushed back within the groove by the stock. The hole in the stripper plate within which the pin slides is notched out to permit the spring to extend forwardly of the stop pin at the bottom thereof. Some of the ditficulties with the Kowalski device are that grease and dirt from the stock can get behind the spring within the groove, thus interferring with the gauging function of the stop pin; the intermittent blows of the stock against the edges of the groove may peen the edges thereof to trap the spring; and the spring itself is subject to deformation, since, to retain its spring qualities, it cannot be hardened. In addition, the forming of the notch in the stripper plate is time consuming, and the location of the notch must be accurately determined.

All of the die-stops of the patents discussed above suffer from several great disadvantages. In all of them, the stop pin slides in a hole formed directly in 'the stripper plate. Some of the difficulties arising from this arrangement are that the hole in the stripper plate must be precisely located, and the mounting holes for the pivot or pivot bracket carefully laid out either by direct measurement or by the use of a separate template;

and that the stripper plate does not admit of hardening, as a practical matter, so that the walls of the stop pin receiving hole are relatively soft and subject to wear as compared with the hardened stop pin. Also, in all of the prior art devices, the pivoting arrangements of the rocker arms of the mechanisms require a substantial margin of the stripper plate between the pivot and the stop pin.

No manually operated work stop mechanism in any respect similar to the device of this invention is known.

One of the objects of this invention is to provide a work stop mechanism which serves as its own template to locate its mounting means.

Another object is to provide a work stop mechanism which admits of gauging adjustment after it is mounted.

Another object is to provide a work stop mechanism which can be mounted on a narrow margin of the plate on which it is mounted.

Another object is to provide an automatic die-stop which is self-cleaning, in which the stop pin and its guide may both be hardened, and which is adapted to operate effectively with thin gauge stock and delicate work.

Another object of this invention is to provide such an automatic die-stop in which the stop pin and biasing means for the pin are easily inserted and removed.

Another object is to provide automatic die-stops which, in combination with a stripper plate having an aperture intermediate the die-stops, are adapted to permit double blanking of the same stock.

Another object is to provide a work stop mechanism which can be employed as a finger stop.

Another object of this invention is to provide a work stop mechanism which has application to devices for gaugingstock for drilling and cut-off operations. And still another object of this invention is to provide a work stop mechanism for dividing and indexing operations.

In accordance with this invention, generally stated, a work stop mechanism is provided which has a mounting bracket made up in one unit of a sole which carries, spaced from one another, a sleeve adapted to receive a stop pin, and a pivot support upon which a rocker arm is pivotally mounted. A stop pin is pivotally mounted on the rocker arm and slides within the sleeve. Between the pivot support and the sleeve, the sole may be provided with a hole through which a fastening means extends. The fastening means preferably takes the form of a mounting stud, taking into a tapped hole in the plate upon which the mounting bracket is mounted, and having a tall head, extending above the level of the pivot support of the mounting bracket.

The rocker arm between the pivot and the stop pin is preferably made in the form of a yoke having arms between which the mounting stud or other fastening means can extend without interfering with the vertical movement of the rocker arm.

In the embodiments in which the work stop mechanism is used as an automatic die-stop, the bore of the sleeve may be made substantially circular at the top (the end of the sleeve adjacent the rocker arm), out flared in one direction toward the bottom of the sleeve to become an oval with two substantially parallel sides. In such a construction, the free end of the stop pin is biased in a direction toward the flared side of the here.

In the embodiments of the work stop mechanism which are not automatic, as for example, when the work stop mechanism is used as a finger stop, the bore may be made uniformly circular and the pin may be pivoted on the rocker arm concentrically or diametrically with respect to the bore.

The stop pin may be given any desired configuration at its free end.

The provision of a sleeve as a part of the mounting bracket, within which sleeve the stop pin slides, has numerous advantages. The sleeve can be made to precise dimensions with respect to the stop pin and can be hardened. The sleeve may be inserted in a hole which is simply bored in the plate upon which the work stop mechanism is mounted. The hole need not be reamed to precise size. It can in fact be made considerably oversize. When the sleeve is inserted within the hole in the plate, the sole itself may be used as a jig or template to locate on the plate the hole or holes to take the fastening means. Even the hole or holes in the mounting bracket sole may be made somewhat oversize with respect to the fastening means to allow gauging adjustment after the work stop mechanism is mounted. The work stop mechanism may be mounted in any desired angular relation to the sleeve, in the plane of the mounting surface of the plate.

In the drawing, Figure 1 is a plan view of a stripper plate upon which are mounted automatic die-stops and manually Operated finger stops constructed in accordance with this invention;

Figure 2 is a sectional view taken along the line 2-2 of Figure 1, showing stock abutting one of the finger stops;

Figure 3 is a sectional view taken along the line 3-3 of Figure 1;

Figure 4 is a sectional view taken along the line 4-4 of Figure 1, showing stock abutting the other finger stop;

Figure 5 is a view similar to that of Figure 4, showing the stock abutting the stop pin of one of the automatic die-stops;

Figure 6 is a fragmentary view, similar to that of Figure 5, showing the stock positioned by a pilot pin and slightly retracted from the position shown in Figure 5;

Figure 7 is a view similar to that of Figure 5, showing the die shoe engaging the adjusting screw of one of the automatic die-stops to raise the stop pin above the stock; 1

Figure 8 is a somewhat diagrammatic plan view showing stock held in punching position by a first finger stop;

Figure 9 is a view similar to that of Figure 8, showing the stock held in punching position by a second finger stop;

Figure 10 is a view similar to that of Figure 9, showing the stock held in punching position by an automatic die-stop;

Figure 11 is a view similar to that shown in Figure 10, showing the stock held in position immediately after blanking;

Figure 12 is a sectional view taken along the line 12-12 of Figure 5;

Figure 13 is a sectional view taken along the line 13-13 of Figure 5;

Figure 14 is an exploded view of an automatic diestop constructed in accordance with this invention;

Figure 15 is a sectional view taken along the line 1515 of Figure l; and

Figure 16 is a somewhat diagrammatic plan view showing the stock, the blanking of which was gauged by one automatic die-stop as shown in Figures 5 through 11, being gauged for intermediate or double blanking by the automatic die-stop shown in Figure 15.

Referring now to the drawings for illustrative embodiments of this invention, 1 represents the stripper plate of a die set. The stripper plate 1 is mounted on a die 2 in such a way as to define between them a channel 4. In the embodiment shown, a thin, round punch 5 and a heavy punch 6 are mounted on a die shoe 10. The punches 5 and 6 are shaped to pass respectively through apertures 15 and 16 in the stripper plate and apertures 17 and 18 in the die. The heavy punch 6 is provided with a pilot or leader pin 7 which is slightly smaller than the round punch 5.

Mounted on a stripper plate 1 are a first automatic die-stop 20, a second automatic die-stop 21, a first finger stop 22 and a second finger stop 23.

All of the work stops 20, 21, 22 and 2.3 have certain elements in common. Each has a mounting bracket 30. The mounting bracket of the embodiment shown is made up of a flat sole 31. The flat sole 31 has a pair of ears 32 bent up at right angles to the plate. The ears 32 are provided with holes 33, aligned to receive a rocker arm pivot pin 34. At an end removed from the cars 32, the sole 31 carries a sleeve 51 which is tightly secured to the plate. When the mounting bracket 31) is mounted on the stripper plate 1, the sleeve 50 extends within a hole 8 in the stripper plate. Between the sleeve 50 and the cars 32, the sole 31 is provided with a mounting stud hole 36.

A rocker arm 4% is in the form of a yoke, with a pair of arms 41, and a closed end 42. The arms 41 are offset outwardly at 43. Between the closed end 42 and the offset 43, the arms are provided with aligned holes 44 adapted to receive the rocker arm pivot pin 34. Near their free ends, the arms 41 are provided with aligned holes through which a stop pin pivot 45 extends. The closed end 42 is provided with a tapped hole 46. A C-shaped clamp 47, proportioned to embrace the rocker arm 40 at the closed end 42 is provided with a hole 48 through which a screw 4-9 passes. The screw 49 takes into the hole 46 in the closed end 42, to tighten the clamp 47.

In each of the illustrative embodiments shown, the mounting bracket 30 is mounted on the stripper plate by means of a stud 37. The stud 37 has a threaded shank 38 which passes through the stud hole 36 in the sole 31 and takes into a tapped hole 9 in the stripper plate. The stud 37 is also provided with a tall coneshaped head 39, truncated and slotted to permit it to be tightened with a screwdriver. The head 39 is of such a height as to be able to support the die shoe above the level of the top of the ears 32.

Referring now to that embodiment of the work stop mechanism of this invention used as an automatic diestop and in particular to the automatic die-stop numbered 21, an exploded view of which is shown in Figure 14, a stop pin 60 is pivotally mounted on the rocker arm 40. The stop pin 60 has a cylindrical shank 61 which, in the embodiment shown, is provided at its lower endwith a nose 62. The nose 62 is beveled slightly along its bottom surface 63. At its other end, the shank 61 carries a housing 65, which, in the embodiment shown, is integral with the shank. The housing 65 is provided with a transverse channel 66, extending perpendicularly to the axis of the shank 61. The channel 66 is wide enough to admit the stop pin pivot 45 and deep enough so that the stop pin pivot 45 meets the closed end of the channel when the shank 61 is flush against the vertical wall of the bore of the sleeve 50, as hereafter described. A recess 64 in the center of the closed end of the channel 66 is formed by boring a hole somewhat larger in diameter than the width of the channel so as also to produce a pair of grooves 67 extending transversely across the walls of the channel 66. The recess 64 and grooves 67 form a seat for a helical spring 69 which, when tightly compressed, lies entirely within the recess 64.

In this embodiment the bore of the sleeve 50 is circular at the upper end of the sleeve (the end embraced by the plate 31) as shown at 70 in Figure 13. The bore flares toward the free end of the sleeve in the direction away from the pivot point of the rocker arm, so as to take the shape at the free end of the sleeve of substantially an oval with two parallel sides, as shown at 72, Figure 12. Thus one curved wall of the bore is vertical, the opposite one, oblique.

In the embodiment of automatic die-stop numbered 20, a stop pin has a shank which is not provided with a nose but is cylindrical throughout its length. The

stop pin 80 is in all other respects the same as the stop pin 60 of the die-stop 21.

The sleeve of the die-stop 20 is also identical with the sleeve of the die-stop 21, except that the bore ofthe sleeve flares in a direction toward the pivot point of the rocker arm, rather than away from it.

Both die-stops 20 and 21 are provided with rocker arm springs 90 mounted on the rocker arm pivot pin 34, and arranged to bias the stop pin carrying end of the rocker arm toward the sleeve 50. Both of the embodiments of automatic die-stop are also provided with adjusting screw brackets 92. Each adjusting screw bracket 92 is made up of a U-shaped piece of wire, the legs 93 of which are substantially parallel. The legs 93 are given a U-bend at right angles to the plane of the closed end of the U, as shown at 95, and again bent at 96 in a direction away from the closed end. The free ends of the legs 93 are clamped between the clamp 47 and the closed end 42 of the rocker arm. An adjusting screw is mounted on the adjusting screw mounting bracket 92 by means of a nut 101 and a tapped slide 102, whereby the adjusting screw 100 may be positioned at any desired point between the closed end of the bracket 92 and the U-bend at 95. I

The finger stops 22 and 23 illustrated in the'accompanying drawing are identical. The sleeve 50 of the finger stops is provided with a straight bore. A wide, axially-extending slot is milled out of the lower end of the sleeve in a direction at right angles to the stop pin pivot to define a U-shaped guideway 145. A stop pin 110 is provided with a cylindrical shank 112. The shank 112 is provided with a simple diametric channel 114 of a width to admit the stop pin pivot 45. In the embodiment shown, the end of the shank 112 opposite the channel 114 takes the form of an inverted L-shaped block 116 having a stem 117 and a short leg 118. The backside of the stem 117 and the forward edge of the short leg 118 of the L-shaped block are flat. These flat surfaces fit slidably but closely between flat faces 121 and 122 of the guideway 145. The forward side of the stem 117 provides a flat stop face 123. The relatively narrow edges of the L-shaped block are rounded on substantially the radius of the sleeve. The sleeves of the finger stops 22 and 23 are so positioned with respect to the channel 4 as to permit a narrow margin of the fiat stop face 123 to extend within the channel 4 when the stop pin 110 is in its lowermost position as shown in Figures 2 and 3.

In each of the finger stops 22 and 23, a spring 119; mounted on the rocker arm pivot pin 34 is arranged to bias the rocker arm in a direction away from the sleeve 50. A handle 120 is mounted on the rocker arm 40 by means of the G-shaped clamp 47. The handle 120 can be of any desired length to allow manipulation of the finger stop from a safe distance beyond the edge of the stripper plate.

The operation of the various work stop mechanisms illustrated will be described in connection with the successive steps of punching a perforated blank from a strip of stock 130 in the die set illustrated. The steps are shown somewhat diagrammatically in Figures 8-11.

In the first operation of this double blanking process, the automatic die-stop 20 is rendered inoperative by chocking up the stop pin, as by inserting a little block beneath the rocker arm between the rocker arm pivot and the stop pin. As indicated in Figure 8, an end 131 of the stock 130 is inserted in the channel 4, the handle of the first finger stop 22 is raised as shown in Figure 3, to lower the stop pin 110, and the stock is pushed into the channel until the edge 131 engages the fiat face 123 of the stop pin 110. The die shoe 10 is then lowered, and the punch 5 punches out a hole 135 in the stock 130. The die shoe 10 is raised, and the handle 120 ofthe finger stop 22 released, permitting the spring 119 to raise the stop pin 110 out of the way of the stock '130. The

3 handle of the second finger stop 23 is then raised and th stock slid farther into the channel 4 until the flat face 123 of the stop pin 110 of the finger stop 23 is engaged by the edge 131 of the stock 130. The die shoe 10 is again lowered. As the die shoe 10 is lowered, the leader pin 7 first enters the hole 135 made by the punch 5 in the first operation. The leader pin 7 thus insures the alignment of the stock with respect to the punch 6, and also with respect to the punch 5, since the leader pin enters the hole before the punch 5 meets the face of the stock. As the lowering of the die shoe 10 continues, the punch 6 punches out a blank 136 while the punch 5 punches out another hole 135. The die shoe 10 is again raised, and the handle of the finger stop 23 is released to allow the spring 119 to raise the stop pin 110.

The blanking out of the blank 136 leaves a patterned aperture 138 in the stock 130. The aperture is necessarily defined by a border of stock as high as the thickness of the stock. In the illustrative embodiment shown the aperture 138 is defined in part by shoulders 140 and 141. The stock is now moved farther along the channel 4 and the rocker arm of the automatic die-stop 21 is rocked manually against the bias of the spring 9!) to permit the end 131 of the stock to clear the stop pin nose 62. The rocker arm is released, and the stop pin 60, biased toward the sleeve 50 by the spring 90 moves against the top of the die 2 between the shoulders 141 and 141) within the patterned aperture 138. As the strip is pushed toward the stop pin 60 the shoulder 140 engages the nose 62 of the stop pin 60 and continued movement of the stock 130 rocks the stop pin 60 back until the shank of the stop pin rests against the vertical wall of the bore of the sleeve 50. In this position the closed end wall of the channel 66 bears against the stop pin pivot 45 to produce a positive vertical alignment of the stop pin. The die shoe 10 is now lowered, and, as in the last described step, the leader pin 7 enters a hole 135. Preferably the leader pin moves the stock 133 back in a direction away from the stop pin 60 a few thousandths of an inch, so as to relieve the stop pin 60 when the actual blanking operation is performed.

As the punch 6 strikes the stock and begins to sheer therethrough, the die shoe 10 pushing down On the head of the adjusting screw 100 rocks the rocker arm 40, raising the stop pin 60 until its bottom surface 63 is above the upper surface of the stock 130. When that position is reached, the nose end of the stop pin springs forwardly above the surface of the stock 131), as shown in dotted lines in Figure 11.

When the die shoe 10 is raised, after the blank 136 is punched out, the spring 90 rocks the rocker arm toward,

its normal position. At this stage, however, the bottom surface 63 of the nose 62 comes to rest on the upper surfaceof the stock 130. When the punch 6 and the leader pin 7 have cleared the aperture 138, the stock is advanced beneath the stop pin. As the stock moves, the nose 62 snaps into the aperture 138. The newly formed shoulder 140 engages the nose 62, and the movement of the stock is arrested as the stop pin again reaches its vertical position. The die shoe is lowered, and the cycle of operation of the die stop 21 is repeated as long as the partly blanked stock is fed in. It can be seen that in producing blanks of the character of the blank 136, there is a good deal of waste material between successive apertures 138 when all of the apertures are oriented in the same direction. It can also be seen that it means are provided for punching, with the same setup, a series of blanks which, to some extent, nest between successive blanks produced in the first operation, a substantial saving in material can be effected.

In accordance with this invention, such a result is obtained by the use of the second automatic die-stop 20.

With the shape of the blank shown in the drawing, this is accomplished by spacing the apertures 138 made in the first blanking operation a distance such that a 7 space is left wide enough to accommodate an inverted aperture. When a length of stock has been once blanked in that manner, it is simply either turned end for end or turned over sothat when the punch 6 punches a blank from the strip, the resultant aperture is inverted in respect to the apertures first formed.

The die-stop 20 is made operative by removing the wedge or pin which held its stop pin away from the stock, and the die-stop 21 is rendered inoperative by inserting the pin or wedge to hold its stop pin out of the way of the stock. The end of the once-blanked stock 'lSb is fed into the channel 4 while the stop pin 80 of the die-stop 2.0 is manually raised to allow the first already formed aperture 133 to pass beyond the stop pin 80. The stop pin 80 is then released and the stock fed to the channel 4 until the shoulder 140 of the second of the already formed apertures 138 engages the stop pin 8t moving it to a vertical position, where the stop pin brings the stock to a halt. Preferably the stock is now manually retracted a few thousandths of an inch to relieve the stop pin 80, although this is not absolutely essential. The die shoe It is now lowered and the punch punches out a hole 135 in the space between the first and second apertures 138. In the course of that operation, as the punch 5 enters the stock 130, the die shoe 10 meets the head of the adjusting screw 1% of the die-stop 20, rocking the rocker arm 43, raising the stop pin 80 above the level of the stock, and allowing the stop pin 80 to spring to a position above the surface of the stock. The stock, of course, is held in position at that point by the punch 5. As the die shoe is again raised, the stop pin 80 comes to rest on the surface of the stock 130, brought to that position by the spring 9i). As the punch 5 clears the stock, the stock is moved forward, the stop pin 80 drops into the following aperture 138 and the stock is brought to a halt by the abutting of the shoulder 140 against the stop pin 89, as the stop pin 8% reaches the vertical position. When the die shoe it? is again lowered, the leader pin 7 of the punch 6 enters the hole 135 made in the preceding operation, and this time the retraction of the stock through a couple of thousandths of an inch s accomplished automatically by the leader pin. The position of the die-stop 2th with respect to the punch 6 is such that a blank 136 is punched out between successive apertures 138, which were made in the blanking operations first performed on the stock. As in the first blanking operations, the cycle of operations in the double blanking just described is automatic after the first blank is punched out, it being necessary only to feed the stock and raise and lower the die shoe.

The beveling of the bottom surface of the nose 62 of the die-stop 21 and of the stop pin 80 of the die-stop not only helps to insure that the stock does not get beneath the stop pin when first it abuts the edge or shoulder of the stock, but also provides a fiat surface of substantial area in contact with the top of the stock so as to provide against grooving or scratching of the stock.

In mounting the die-stops 20 and 21 or the finger stops 22 and 23 on the stripper plate, it is only necessary to calculate their desired positions with respect to apertures 15 and 16 through which the punches 5 and 6 are to go, and to bore holes 8 in the stripper plate to receive the sleeves 50 of the die-stops. A sleeve 50 is inserted in a hole 8, and the sole 31 used as a template to locate the hole 9 in the stripper plate through the stud hole 36 in the sole. If it should happen that the sleeve 50 is somewhat inaccurately placed, the hole 8 may be bored oversize; for example, a thirty-second of an inch larger than the diameter of the sleeve. The stud hole 36 may also be made similarly oversize with respect to the shank 38 of the stud 37, and the sleeve can be shifted around in any direction to correct for the error/in location. The stud is then tightened to maintain the sole, hence the sleeve, in proper position. It can be seen that such an arrangement does not interfere with the accuracy or efficiency of the work stop, because the sleeve and the pin remain unaffected. That is to say, the tolerances between the hardened sleeve and the hardened pin are the same no matter whether the sleeve is mounted snugly within a hole or is supported'only by the sole 31.

The die-stops and finger stops may be oriented in any direction in the horizontal plane with respect to the holes 8. This is advantageous both in making the margin requirements more flexible and in those blanking operations wherein the shoulder against which the stop pin is to abutt is oblique with respect to the direction of travel of the stock. In such an operation, the stop mechanism can be so oriented that the thrust of the shoulder against the stop pin is perpendicular to the stop pin pivot and rocker arm pivot pin. Alternatively or additionally, the shoulder engaging end of the stop pin may be shaped to meet the shoulder squarely.

The stop mechanisms also may be used in any position with respect to the horizontal; for example, they operate well upside down, as in compound die sets wherein the stripper plate underlies a die.

It can be seen that some of the features of the auto matic die-stop and of the finger stops can be combined to produce work stop mechanisms for use in various other applications besides die sets. For example, a work stop mechanism can be used in drilling operations where holes are desired at regular spaced intervals along a piece of stock. In such an application, the stock may be either in the form of a strip or in some other shape as, for example, circular. In the former case, an arrangement similar to that of the stripper plate described may be provided wherein a channel is defined between a plate on which a Work stop mechanism is mounted (and through a hole in which a drill moves) and an underlying plate. The stock is fed into the channel. The work stop mechanism may have a sleeve with a straight bore. A rocker arm spring may be arranged to bias a stop pin sliding in the straight bore against the underlying plate or the stock, as the case may be. The stock-engaging end of the stop pin may be given any desired configuration. For example, it can be made very small to fit into a small bored hole, or it may be made larger than the sleeve, by shortening the sleeve, and, if necessary, countersinking the under side of the plate to make room for an enlarged head. The drill should be located between the feed end of the channel and the stop mechanism. In the operation of such a work stop mechanism, a hole bored in the strip of stock by the drill is in such a position as to permit the stop pin to engage a boundary of the hole as the strip is fed in the channel. Such a hole is bored, the rocker arm is rocked manually to raise the stop pin until the strip of stock has moved beneath the stop pin, the rocker arm is released, and the stop pin springs into the bored'hole when it comes along. The process may be repeated as often as is necessary. Instead of a single drill, a gang of any number of drills may be used, with one or more work stop mechanisms. In boring spaced holes in a piece of circular stock, a plate may be provided upon which a work stop mechanism, like that which has just been described, is mounted. The plate and the circular stock are mounted concentrically so that either the stock can be rotated with respect to the plate or the plate with respect to the stock. Either radially or axially directed holes can be bored at regular intervals about the center of the stock. Such an arrangement can be used for indexing or dividing.

It can be seen that while punching and drilling operations have been described, the work stop mechanisms of this invention have application in many other recessing operations. The recess produced need be very small indeed, since the nose of a stop pin may be given any desired configuration. The work stop mechanisms are also adaptable to both heavy work and very fine light work such as jewelry and the like.

Thus, it can be seen that a work stop mechanism is provided which is simple, eflicient, versatile, quickly and easily installed, adjustable after mounting and dependable.

Having thus described my invention what is claimed and desired to be secured by Letters Patent is:

1. A work stop mechanism comprising a mounting bracket having a sole, a sleeve carried by said sole, and a pivot support carried by said sole and spaced along said sole from said sleeve; a rocker arm pivotally mounted on said pivot support and a stop pin slideably mounted within said sleeve and pivotally carried by said rocker arm.

2. In a work stop mechanism, the improvement comprising a mounting bracket having a sole, a sleeve carried by said sole, and a pivot support carried by said sole and spaced along said sole from said sleeve.

3. In a work stop mechanism of the character in which a rocker arm is pivotally mounted on a mounting bracket, the improvement comprising said mounting brackets having a sole carrying a sleeve and a pivot support spaced along the sole from the sleeve and having a fastener-receiving hole located between said sleeve and said pivot support.

4. A work stop mechanism of the character described in claim 1, wherein the bore of the sleeve is substantially circular at the top, but flares in one direction toward the bottom of said sleeve to form a substantially oval bore with two substantially parallel sides.

5. A work stop mechanism of the character described in claim 4 wherein the stop pin has a cylindrical shank and its free end is normally biased toward the flared direction of the bore.

6. In a work stop mechanism having a stop pin, the

improvement comprising a mounting bracket having a sole and a sleeve carried by said sole, said pin being slidably mounted in said sleeve.

7. In a work stop mechanism having a stop pin, the improvement comprising a mounting bracket having a sole and a sleeve carried by said sole, said pin being slidably mounted in said sleeve, said sole being provided with a fastener-receiving hole.

8. A work stop mechanism comprising a mounting bracket having a sole, a sleeve carried by said sole and depending therefrom and a pivot support on the side of said sole opposite the side from which said sleeve depends; a rocker arm pivotally mounted on said pivot support on a pivot pin carried by said pivot support; a

. stop pin slideably mounted within said sleeve and pivotally carried by said rocker arm, the bore of said sleeve being substantially circular at the top but flaring in a direction at right angles to the pivot of said rocker arm toward the bottom of said sleeve to form a substantially oval bore with two substantially parallel sides; and means for biasing the free end of said stop pin toward the flared direction of the bore.

9. A work stop mechanism of the character described in claim 8 wherein the means for biasing the stop pin comprise a pivot on said rocker arm upon which the stop pin is shiftably mounted, said pivot being substantially diametric with respect to said sleeve, and a spring bearing against said pivot and against said stop pin to move said stop pin away from said pivot.

10. In combination, a plate; a work stop mechanism having a sole carrying a sleeve mounted within a hole in the said plate and a pivot support spaced along said sole from said sleeve, said sole having a stud receiving hole between said sleeve and said pivot support; and a stud, said stud having a head of a diameter greater than the said stud receiving hole and a threaded shank of a diameter substantially less than that of the said stud receiving hole, said threaded shank extending through said stud receiving hole into a tapped hole in said plate.

11. In combination with a plate having an aperture therein, a first work stop mechanism mounted on said plate at one side of said aperture and a second work stop mechanism mounted on said plate on the opposite side of said aperture, each of said work stop mechanisms comprising a mounting bracket having a sole, a sleeve carried by said sole, and a pivot support carried by said sole and spaced along said sole from said sleeve, a rocker arm pivotally mounted on said pivot support and a stop pin slideably mounted within said sleeve and pivotally carried by said rocker arm, each of said work stop mechanisms having its sleeve adjacent the aperture and its rocker arm pivot away from said aperture with respect to said sleeve, the bore of the sleeve of the second work stop mechanism flaring downwardly toward the aperture and away from the rocker arm pivot and the bore of the sleeve of the first work stop mechanism flaring downwardly away from said aperture and toward the rocker arm pivot.

References Cited in the file of this patent UNITED STATES PATENTS 361,065 James Apr. 12, 1887 882,125 Rigby Mar. 17, 1908 915,042 Robinson Mar. 9, 1909 1,396,185 Furber Nov. 8, 1921 1,495,989 Danly June 3, 1924 2,219,060 West Oct. 22, 1940 

